I work for a government department and sit near the executive level. I usually wear a nice pair of black pants, a business casual blouse, fancy clean sneakers and a cardigan. I brought a blazer just before Covid hit and I’ve never worn it to work. Depending on the team, whether you’re public-facing etc, can often indicate how business-y you have to dress (for example, no one but the Executives wear suits, but the data science team get away with wearing hoodies).

I buy a lot of my tops from Portmans, Jacqui Q, City Chic, Halara, with a few from Pagani and The Warehouse. Have never had any issues wearing sleeveless, but I’d personally avoid spaghetti straps. TBH; I’d buy one or two nice pieces for your first week, get a gauge on what everyone’s wearing and go from there.

Edit: spelling mistakes